From vertical silos to integrated care: administrative agility and normalization of HIV services in Tamil Nadu, India

BACKGROUND: While India's HIV epidemic discloses substantial inter-state heterogeneity, Tamil Nadu (TN) achieved one of the country's earliest and most sustained reversals in transmission. Once a high-burden state, TN successfully decoupled its trajectory from other high-prevalence southern regions. This review examines the 'Tamil Nadu Model,' benchmarking its performance against West Bengal and global high-performers to identify specific drivers of success while comparing it with Karnataka, Maharashtra, and undivided Andhra Pradesh. METHODS: We synthesized longitudinal data (2000-2024) from HIV Sentinel Surveillance (HSS), IBBS, NACO Spectrum estimates, and NFHS reports. Using a Strategic Blueprints (SB) framework, we analyzed 13 key epidemiological and health-system indicators, including TB-HIV collaborative care. We compared Tamil Nadu's performance with Karnataka, Maharashtra, undivided Andhra Pradesh, and West Bengal, as well as international benchmarks including Thailand, New South Wales, and KwaZulu-Natal. RESULTS: Tamil Nadu recorded a 94% reduction in annual new infections, with adult prevalence falling from 1.15% (2000) to 0.16% (2024). TN became the first major Indian state to achieve the WHO threshold for eliminating vertical transmission (< 5%). Comparative analysis demonstrates that TN's "Administrative Agility" facilitated faster declines than low-intensity states like West Bengal. Furthermore, integrating TB-HIV services via the Ni-kshay platform and "Four-S" screening protocols achieved near-universal status awareness among TB patients, accelerating progress toward UNAIDS 95-95-95 targets. CONCLUSION: Tamil Nadu's trajectory proves that administrative agility and institutional normalization are more effective than vertically siloed interventions. Its ability to outperform regional peers and global benchmarks underscores the robustness of its Strategic Blueprints. As programs transition toward 2030, integrating HIV care with non-communicable disease and TB management offers a scalable road-map for sustained control. Ultimately, shifting from state-level data to global policy lessons positions the "Tamil Nadu Model" as a transferable framework for ending AIDS in resource-limited settings worldwide.